lamont
Contributor
Also, as you will no doubt agree, there are many different configurations, and likewise there are peoplethat are not right handed but left handed. Which in turn, would mean that potentially those divers are doing a number of things in reverse!?
In the cave diving configuration popularized by Hogarth, DIR, NAUI-Tech, etc the important issue is not the handedness of the diver, but the fact that the right post on the manifold will not roll off. That means that the long hose comes off the right side to prevent a roll off when donating gas. Since you don't want to trap the long hose, the SPG hose goes on the other side.
It might have made sense to have the left post use a reverse threaded valve so that it also would not roll off, but changing now would cause too much potential confusion.